In an ignition coil used for an internal combustion engine, a primary coil is wound on a resinous primary spool and a secondary coil is wound on a resinous secondary spool. The primary and secondary coils are accommodated in a resinous coil case to form the ignition coil. The primary coil can be formed in a cylindrical shape using a self-fusing copper wire without the primary spool.
For example, JP-A-8-55742 discloses a coil case of an ignition coil for an internal combustion engine. The coil case is constructed by integrally forming a container for accommodating therein a transformer for generating a high voltage, a cylindrical primary bobbin for holding a primary winding of the transformer, and a connector for connection of an electric signal with an external device for controlling the high voltage. The primary winding using the self-fusing wire is mounted on the primary bobbin.
However, in the conventional ignition coil as disclosed in JP-A-8-55742, a secondary spool (secondary bobbin) and the connector for connecting the ignition coil to an external electronic control unit (ECU) or the like are separately molded and assembled. This arrangement is not sufficient to decrease the number of components of the ignition coil. When the secondary spool is assembled to the connector, measures are required in order to stably connect a low-voltage side winding end of the secondary coil wound on the secondary spool to a terminal (or a fitting member) for connection with a conducting pin of the connector.